Lack of Dystrophin Affects Bronchial Epithelium inmdxMice

DDAH1 Promotes Lung Endothelial Barrier Repair by Decreasing Leukocyte Transendothelial Migration and Oxidative Stress in Explosion-Induced Lung Injury

Explosion-induced injury is the most commonly encountered wound in modern warfare and incidents. The vascular inflammatory response and subsequent oxidative stress are considered the key causes of morbidity and mortality among those in blast lung injury. It has been reported dimethylarginine dimethylaminohydrolase 1 (DDAH1) plays important roles in regulating vascular endothelial injury repair and angiogenesis, but its role in explosion-induced injury remains to be explained. To explore the mechanism of vascular injury in blast lung, 40 C57BL/6 wild type mice and 40 DDAH1 knockout mice were randomly equally divided into control group and blast group, respectively. Body weight, lung weight, and dry weight of the lungs were recorded. Diffuse vascular leakage was detected by Evans blue test. The serum inflammatory factors, nitric oxide (NO) contents, and ADMA level were determined through ELISA. Hematoxylin-eosin staining and ROS detection were performed for histopathological changes. Western blot was used to detect the proteins related to oxidative stress, cell adhesion molecules and leukocyte transendothelial migration, vascular injury, endothelial barrier dysfunction, and the DDAH1/ADMA/eNOS signaling pathway. We found that DDAH1 deficiency aggravated explosion-induced body weight reduction, lung weight promotion, diffuse vascular leakage histopathological changes, and the increased levels of inflammatory-related factors. Additionally, DDAH1 deficiency also increased ROS generation, MDA, and IRE-1α expression. Regarding vascular endothelial barrier dysfunction, DDAH1 deficiency increased the expression of ICAM-1, Itgal, Rac2, VEGF, MMP9, vimentin, and N-cadherin, while lowering the expression of occludin, CD31, and dystrophin. DDAH1 deficiency also exacerbated explosion-induced increase of ADMA and decrease of eNOS activity and NO contents. Our results indicated that explosion could induce severe lung injury and pulmonary vascular insufficiency, whereas DDAH1 could promote lung endothelial barrier repair and reduce inflammation and oxidative stress by inhibiting ADMA signaling which in turn increased eNOS activity.

Mild Aerobic Exercise Training Hardly Affects the Diaphragm of mdx Mice

In the mdx mice model of Duchenne Muscular Dystrophy (DMD), mild endurance exercise training positively affected limb skeletal muscles, whereas few and controversial data exist on the effects of training on the diaphragm. The diaphragm was examined in mdx (C57BL/10ScSn-Dmdmdx) and wild-type (WT, C57BL/10ScSc) mice under sedentary conditions (mdx-SD, WT-SD) and during mild exercise training (mdx-EX, WT-EX). At baseline, and after 30 and 45 days (training: 5 d/wk for 6 weeks), diaphragm muscle morphology and Cx39 protein were assessed. In addition, tissue levels of the chaperonins Hsp60 and Hsp70 and the p65 subunit of nuclear factor-kB (NF-kB) were measured in diaphragm, gastrocnemius, and quadriceps in each experimental group at all time points. Although morphological analysis showed unchanged total area of necrosis/regeneration in the diaphragm after training, there was a trend for larger areas of regeneration than necrosis in the diaphragm of mdx-EX compared to mdx-SD mice. However, the levels of Cx39, a protein associated with active regeneration in damaged muscle, were similar in the diaphragm of mdx-EX and mdx-SD mice. Hsp60 significantly decreased at 45 days in the diaphragm, but not in limb muscles, in both trained and sedentary mdx compared to WT mice. In limb muscles, but not in the diaphragm, Hsp70 and NF-kB p65 levels were increased in mdx mice irrespective of training at 30 and 45 days. Therefore, the diaphragm of mdx mice showed little inflammatory and stress responses over time, and appeared hardly affected by mild endurance training. J. Cell. Physiol. 232: 2044-2052, 2017. © 2016 Wiley Periodicals, Inc.